Integrated deposition of thin film layers in cadmium telluride based photovoltaic module manufacture

Abstract

Apparatus and processes for thin film deposition of semiconducting layers in the formation of cadmium telluride thin film photovoltaic device are provided. The apparatus includes a series of integrally connected chambers, such as a load vacuum chamber connected to a load vacuum pump; a sputtering deposition chamber; a vacuum buffer chamber; and, a vapor deposition chamber. A conveyor system is operably disposed within the apparatus and configured for transporting substrates in a serial arrangement into and through the load vacuum chamber, the sputtering deposition chamber, the vacuum buffer chamber, and the vapor deposition chamber at a controlled speed. The sputtering deposition chamber; the vacuum buffer chamber; and the vapor deposition chamber are integrally connected such that the substrates being transported through the apparatus are kept at a system pressure less than about 760 Torr.

1 - 10 . (canceled) 
     
     
         11 . A process of manufacturing a thin film cadmium telluride thin film photovoltaic device, the process comprising:
 transporting a substrate into a load vacuum chamber connected to a load vacuum pump;   drawing a vacuum in the load vacuum chamber using the load vacuum pump until an initial load pressure is reached in the load vacuum chamber;   transporting the substrate from the load vacuum chamber into a sputtering deposition chamber, wherein the sputtering deposition chamber comprises a target that comprises cadmium sulfide;   sputtering the target to deposit a cadmium sulfide layer on the substrate in a sputtering atmosphere including a plasma, wherein the plasma ejects atoms from the target to deposit onto the substrate;   transporting the substrate from the sputtering deposition chamber into a vacuum buffer chamber connected to a buffer vacuum pump;   drawing a vacuum in the vacuum buffer chamber using the buffer vacuum pump to form a buffer atmosphere, wherein the buffer vacuum pump removes residual atoms ejected from the target from the buffer atmosphere;   transporting the substrate from the vacuum buffer chamber into a vapor deposition chamber comprising a source material, wherein the source material comprises cadmium telluride; and,   depositing a cadmium telluride layer on the cadmium sulfide layer by heating the source material to produce source vapors that deposit onto the cadmium sulfide layer on the substrate,   wherein the substrate is transported through the load vacuum chamber, the sputtering deposition chamber, the vacuum buffer chamber, and the vapor deposition chamber at a system pressure less than 760 Torr.   
     
     
         12 . The process as in  claim 11 , wherein the vapor deposition chamber comprises a receptacle for holding a the source material, a heating manifold for heating the receptacle such that the source material vaporizes into source vapors, and a deposition plate defining holes through which the source vapors pass for deposition of the cadmium telluride layer over the cadmium sulfide layer on the substrate. 
     
     
         13 . The process as in  claim 11 , wherein the vacuum buffer chamber further comprises heaters configured to heat the substrate to a vapor deposition temperature. 
     
     
         14 . The process as in  claim 11 , further comprising:
 transporting the substrate from the vacuum buffer chamber into a heating chamber;   heating the substrate to a vapor deposition temperature; and, transporting the substrate from the heating chamber to the vapor deposition chamber.   
     
     
         15 . The process as in  claim 11 , further comprising:
 transporting the substrate from the load vacuum chamber into a preliminary sputtering chamber;   sputtering a resistive transparent layer on the substrate;   transporting the substrate from the preliminary sputtering chamber into the sputtering deposition chamber to deposit a cadmium sulfide layer on the resistive transparent layer.   
     
     
         16 . The process as in  claim 15 , wherein the preliminary sputtering deposition chamber comprises a preliminary target, wherein the preliminary target is sputtered to deposit a resistive transparent layer on the substrate, the resistive transparent layer comprising zinc tin oxide. 
     
     
         17 - 20 . (canceled)